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Abstract

The work herein has been divided into five sections.
In the first section, a new method of converting N-aroyl-
hydrazines to hydrazidic halides is described.
The second section deals with the products of reaction
of hydrazidic halides with thioacetate ion in acetonitrile
at room temperature. A number of new acetylthiohydrazides
has been isolated together with corresponding hyclrazidic
sulphides. Examination of x-ray data for bis-[~ -(2,6-
dibromophenylhydrazono) - benZYl] sulphide revealpd the
symmetrical structure as the most probable.
In the third section, which consists of the three
subsections, the synthesis of the 4H-l,3,4 benzothiadiazine
ring system has been extended to 4H-l,3,4 benzothiadiazines
with substituents in the 5 and 6-positions. Extension of
synthesis also involves 4H-l,3,4 benzothiadiazines with mora
than one substituent. Nuclear magnetic resonance spectra of
5 and 6 substituted 4H-l,3,4 benzothiadiazines have been
,.
recorded. The section ends with a discussion of the mass
spectra of some 4H-l.3,4 benzothiadiazines.
In the fourth section, which is divided into two sub-
-sections, preparation of 7-nitro substituted 4H-l,3,4
benzothiadiazine from N-thiobenzoyl hydrazine and2,4-dinitro
-fluorobenzene is found to be satisfactory. Thiohydrazides
react with acetic anhydride, in some cases, to give products
identical with acetylthiohydrazides obtained from the
hydrazidic halides with thioacetate ion at room temperature.
In most of the cases thiohydrazides are found to give
anomalous products on reaction with acetic anhydride and
mechanisms for their formation are discussed.
In the fifth section, which forms three subsections,
the 4H-l,3,4 benzothiadiazine ring system with a halogen
substituent in the 7-position undergoes electrophilic attack
preferentially in 5-posi tion. \fuen the 5-posi tion is occupied
by a halogen atom, electrophilic substitution occurs at the
7-position of 4H-l,3,4 benzothiadiazine ring system.
Substitution at the 4-nitrogen atom in 4H w l,3,4 benzo-
-thiadiazine is extremely slow, probably due to delocalisa-
-tion of the nitrogen lone pair in the system. Oxidation
of 4H-l,3,4 benzothiadiazines occurs at the sulphur atom
under relatively mild conditions.
t The Appendix deals with the reaction of N-benzoyl-N -
-(2,5-dibromophenyl)hydrazine with p-nitrothiophenol~ The
proposed p-nitrothiophenoxy - intermediate may undergo
benzothiadiazine formation in a proton exchange system.